JPH0468042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a material for producing a cladding by hot rolling or extrusion (hereinafter collectively referred to as hot rolling).

[Conventional technology]

Conventionally, methods for manufacturing long seamless double-walled pipes include plug mill rolling, Atsel mill rolling, and hot extrusion. In all of these methods, in order to bring the mating surfaces into close contact, when assembling the materials, the outer diameter of the inner layer material is made larger than the inner diameter of the outer layer material and the material is press-fitted, or a gap is created between the mating surfaces of both materials. We are working on a way to fit them together. Both ends of this mating surface are welded and sealed to prevent oxidation during heating and pipe manufacturing prior to hot pipe manufacturing, and further treatment is performed such as removing air existing on the mating surface or performing argon purge. It's summery.

Specifically, Japanese Patent Publication Nos. 57-181720 and 59-
The one published in Publication No. 179212 is known.

On the other hand, this type of double pipe is made of different materials to achieve desired characteristics both inside and outside. Therefore, there is always a difference in coefficient of linear expansion between the materials for the inner and outer layers. Under such conditions, if the inner and outer layer materials are directly seal-welded at their ends, when the materials are heated, the seal weld will break due to the difference in linear expansion coefficient, and the mating surfaces will be oxidized, causing problems after pipe manufacturing. This results in a situation where the two materials are not firmly bonded metallurgically.

Therefore, in Japanese Patent Publication No. 57-154, a technique (hereinafter referred to as (referred to as prior law).

[Problem to be solved by the invention]

However, the above-described prior method requires groove machining, which requires a great deal of effort and time. In addition, the position and depth of the groove must be determined for each product, and if there is a large difference in linear expansion coefficient between the inner and outer materials, the groove may not be able to absorb the expansion sufficiently.

Therefore, the main purpose of the present invention is to simplify pre-processing compared to previous methods, and to always make the gap between the base material and composite material airtight even if the difference in coefficient of linear expansion is large, so that the required internal and external The objective is to provide a material that can provide the bonding strength of both materials.

Another object of the present invention is to provide a material for producing hot-rolled clad steel that can prevent damage to the metal cap even if the material is subjected to external forces during transportation or the like.

[Means to solve the problem]

The above problem is solved by loosely fitting a composite material into a cylindrical base material, and seal-welding the base material and composite material at both longitudinal ends to seal the gap, and at least one end of the composite material fits into the gap. This problem can be solved by covering the cap with a flexible metal cap and sealing and welding the surrounding area.

In addition, a rigid protective material with a longer protrusion than the flexible metal cap is bonded to at least one end of the base material and composite material at least on one end of the above-mentioned material to protect the flexible metal cap. It is preferable.

[Effect]

In the present invention, since the gap between the base material and the composite material is sealed and welded at both ends, oxidation caused by hot rolling can be prevented by using oxidation prevention treatment such as deaeration before hot rolling. It is possible to obtain a clad steel material in which the interface between the two is firmly joined.

In addition, even if the amount of expansion of the base material and composite material differs due to the difference in linear expansion coefficient between the base material and composite material due to heating before rolling of the material, the metal cap is flexible, so Since the metal cap is deformed, the sealability of the gap at the end where the metal cap is provided is not impaired. Further, the metal cap can be easily fixed by manual welding or the like. Therefore, this method is simpler than the previous method, which involves machining grooves.
Furthermore, since there is a large degree of freedom in deforming the metal cap, there is no need to prepare a dedicated metal cap each time the base material and composite material used are changed, making it versatile. Further, it is preferable that the metal cap has a large degree of freedom in deformation in order to ensure airtightness.

On the other hand, if a metal cap is provided at at least one end of the material in accordance with the present invention, the metal cap may break when it comes into contact with the pusher or subsequent material during transportation of the material, resulting in a loss of airtightness. Therefore, if a protective material is provided at the end of the material where the metal cap is provided, even if an external force is applied,
Since the protective material receives external force, damage to the metal cap can be prevented.

[Specific structure of the invention]

The present invention will be explained in more detail below with reference to the concrete examples shown in the drawings. In the following explanation, double-pipe pipes are representatively shown, but as shown in Fig. 4, triple-pipe pipes, multiple pipes with more layers, or composite material inserted into the base material can also be used. Instead of a tube, it may be a solid rod as shown in FIG. The resulting material is also called billet.

Figure 1 shows an example of a double tube billet, in which a composite material 2 constituting the inner tube is inserted into a base material 1 constituting the outer layer with a gap G, and the gap G at one end (left end) is After a V-shaped groove is formed in advance, seal welding 3 is applied. At the other end, a ring-shaped flexible thin metal cap 4 is provided across the base material 1 and composite material 2 to cover the gap G, and the outer and inner edges of the metal cap 4 are sealed by the seal weld 5A. ,5
B has been done. In addition, in the example shown in FIG. 1, since the billet is made by extrusion pipe manufacturing, a radius is formed on the outer periphery of the end that becomes the tip during extrusion.

On the other hand, since the gap G needs to be maintained at a reduced pressure or vacuum, it is preferable to form a deaeration plug 6 in a part of the metal cap 4, as shown in FIG. It is good to have .

Such a billet is manufactured as follows. That is, first, the base material 1 and the composite material 2 are formed, and the metal cap 4 with the deaeration plug 6 is also manufactured. Thereafter, beveling is performed on the mating surfaces of the tips of the base material 1 and the composite material 2. Next, the composite material 2 is inserted into the base material 1, and the tip is seal welded 3, and a metal cap is placed on the rear end, and the seal weld 5 is applied.
Perform A and 5B. After that, the air is removed by a vacuum pump (not shown) through the deaeration stopper 6, and the opening 6 is closed off with the stopper body 7. In this case, instead of using the plug body 7, the degassing plug 6 can be sealed by crushing the center portion in the length direction or by integrating it by welding. After this work has been completed, the billet can be heated and then hot-tubed to produce a clad pipe.

In addition to extrusion, the pipe may be made by piercing rolling, in which case the tip of the billet is not rounded.

By heating the above billet, base material 1 and composite material 2
Due to the difference in linear expansion coefficient between
As shown in the figure, if there are differences in length or diameter,
The metal cap 4 deforms as shown in each figure and maintains an airtight state.

Figure 4 shows a triple billet made by coaxially inserting the first composite material 2A and the second composite material 2B into the base material 1. In this case, the gaps G ₁ and G ₂ are commonly A cap 4 is provided to cover the base material 1 and the second composite material 2B. In addition, two metal caps, one with a large diameter and one with a small diameter, are prepared, and each cap is placed between the base material 1 and the first composite material 2A, and between the first composite material 2A and the second composite material 2B. It is also within the gist of the present invention to seal the gap _G1 and the gap _G2 .

FIG. 5 shows an example in which the composite material 2' used to manufacture a clad rod by extrusion and a clad pipe by piercing and rolling is a solid bar. In this case, a ring-shaped metal cap may be used as shown in the example in Figure 1, but a mandrel is not inserted into the hollow part of the billet prior to extrusion, as in the case of manufacturing clad pipes by extrusion. Since there is no cap, a disk-shaped metal cap 4' is provided.

The vertical cross-sectional shape of the metal cap is shown in Figure 6 a, b,
It can take any suitable shape as shown in c. The metal cap is generally made by punching and pressing a thin steel plate, but may be made of other materials. The wall thickness is preferably about 2 to 9 mm in terms of deformability and breakage prevention.

On the other hand, when the billet with a metal cap is being transported, the rear end may be pushed by a pusher, and the metal cap may break, resulting in loss of airtightness.

Therefore, as shown in FIGS. 8 to 13, a rigid protective material 10 longer than the protruding length of the metal caps 4, 40 is
It is desirable to join the billet to the billet. 8th
The examples shown in FIGS. 1 to 10 are examples in which a ring-shaped protective material 10 made of carbon steel or the like is joined to a base material 1, and the examples shown in FIGS. The protective material 10 covers the outer edge of the end surface of the base material 1 and the composite material 2.
The inner edge of the end surface, or the thick center of the end surface of the base material 1 or the composite material 2 end surface may be used as appropriate. Further, one of the peripheral edges of the metal caps 4, 40 may be seal-welded to the protective material 10, and this example also constitutes a specific example of the present invention. Furthermore, although the protective material 10 in each of the above examples has a single ring shape, it may be a plurality of rings, or a plurality of bar-like protrusions joined at appropriate positions.

By the way, in all the above examples, one end has a seal welded part 3 in the grooved part, but as shown in FIG. 14, the gap G is sealed with metal caps 4, 4 at both ends. You can do it like this.

〔Example〕

Next, Examples will be shown to clarify the effects of the present invention.

Example 1 Ten billets each having a length of 1100 mm as shown in FIG. 1 were manufactured.

The material of the outer tube is carbon steel, outer diameter 288mmφ x inner diameter 154mm.
The dimensions are mmφ. The inner tube is made of SUS316 and has an outer diameter of 153mmφ and an inner diameter of 105mmφ. In addition, there are 5 ring-shaped metal caps made of the same material as the outer tube.
Prepare 5 pieces made of the same material as the inner tube, and their dimensions are as follows:
All rings have a width of 30mm, a height of 10mm, and a wall thickness of 3mm. Welding was done by hand on both ends, and the temperature was 10 ^-5 Torr.
A vacuum was drawn through the degassing stopper until the temperature reached 1.

After heating such a billet to 1200℃, the outer diameter becomes 125
A clad tube with mmφ x 95 mmφ internal diameter was obtained by hot tube extrusion. All 10 pieces obtained had strong metallurgical bonding.

(Comparative Example) A separately prepared billet was made into a pipe under the same conditions as in Example 1 except that no evacuation was performed. As a result, peeling caused by the oxide film was observed over the entire length.

Example 2 When the billet of Example 1 was bonded with a ring-shaped protective material with an outer diameter of 288 mmφ, an inner diameter of 200 mmφ, and a protrusion height of 50 mm with the structure shown in Figure 8, it was put on an actual production line. No damage to the metal cap was observed inside.

〔Effect of the invention〕

As described above, according to the present invention, it is extremely easy to process the material for airtight sealing, and even if the material is deformed due to heating, airtightness can always be maintained. Also,
By having a protective material, damage to the metal cap can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of the present invention, FIGS. 2 and 3 are longitudinal sectional views showing an example of the deformed state after heating, and FIGS. 4 and 5 are longitudinal sectional views of other billet examples. Figures 6a, b, and c are longitudinal cross-sectional views of metal cap examples, and Figure 7 shows a metal cap with a sealing plug. Figure a is a vertical cross-sectional view, Figure b is a right side view, and Figure 8
Figures 1 to 13 are longitudinal sectional views of an example of a billet to which a protective material is bonded, and Fig. 14 is a longitudinal sectional view of a billet having metal caps at both ends. 1... Base metal, 2, 2A, 2B... Mixed material, 3... Seal welded part, 4, 4', 40... Metal cap, 5A,
5B... Seal welded part, 10... Protective material, G, G ₁ ,
G ₂ ,...Gap.

Claims (1)

[Scope of Claims] 1. A composite material is loosely fitted into a cylindrical base material, and both ends in the longitudinal direction are joined by seal welding to seal the base material and the composite material, at least one of which A material for manufacturing hot-rolled clad steel, characterized in that the ends are covered with flexible metal caps and the periphery is sealed and welded. 2. The method according to claim 1, wherein a rigid protective material having a longer protrusion length than the flexible metal cap is bonded to at least one of the base material and the composite material at at least one end to which the flexible metal cap is bonded. Hot rolled clad steel manufacturing material.